There has been known an auto-leveling control in which a position of an optical axis of a vehicle headlamp is adjusted automatically in accordance with an inclination angle of a vehicle so as to change an illumination direction of the headlamp.
In the auto-leveling control, the position of the optical axis of the headlamp may be adjusted based on a pitch angle of the vehicle which is derived from an output value of a vehicle height sensor. On the other hand, JP 2012-030782 A (corresponding to U.S. 2012/0002430 A1) and JP 2012-030783 A (corresponding to U.S. 2011/0317439 A1) describe a vehicle lamp control apparatus in which auto-leveling control is carried out using an inclination sensor such as an acceleration sensor.